function mynew(Classname) {
  let newobj = {};
  newobj.__proto__ = Classname.prototype;
  // 把参数转化成数组 且只取第二个开始的参数
  let args = Array.from(arguments).slice(1);
  Classname.call(newobj, ...args);
  return newobj;
}
function Person(name, age) {
  this.name = name;
  this.age = age;
}
let person = mynew(Person, "coderqian", 23);
console.log(person);
